Single sessions of transcranial direct current stimulation and transcranial random noise stimulation exert no effect on sleepiness in patients with narcolepsy and idiopathic hypersomnia.

Background: Hypersomnia poses major challenges to treatment providers given the limitations of available treatment options. In this context, the application of non-invasive brain stimulation techniques such as transcranial electrical stimulation (tES) may open up new avenues to effective treatment. Preliminary evidence suggests both acute and longer-lasting positive effects of transcranial direct current stimulation (tDCS) on vigilance and sleepiness in hypersomniac patients. Based on these findings, the present study sought to investigate short-term effects of single sessions of tDCS and transcranial random noise stimulation (tRNS) on sleepiness in persons suffering from hypersomnia. Methods: A sample of 29 patients suffering from narcolepsy or idiopathic hypersomnia (IH) was recruited from the Regensburg Sleep Disorder Center and underwent single sessions of tES (anodal tDCS, tRNS, sham) over the left and right dorsolateral prefrontal cortex on three consecutive days in a double-blind, sham-controlled, pseudorandomized crossover trial. The primary study endpoint was the mean reaction time measured by the Psychomotor Vigilance Task (PVT) before and directly after the daily tES sessions. Secondary endpoints were additional PVT outcome metrics as well as subjective outcome parameters (e.g., Karolinska Sleepiness Scale; KSS). Results: There were no significant treatment effects neither on objective (i.e., PVT) nor on subjective indicators of sleepiness. Conclusion: We could not demonstrate any clinically relevant effects of single sessions of tDCS or tRNS on objective or subjective measures of sleepiness in patients with hypersomnia. However, we cannot exclude that repeated sessions of tES may affect vigilance or sleepiness in hypersomniac patients.

Narcolepsy risk loci outline role of T cell autoimmunity and infectious triggers in narcolepsy.

Narcolepsy type 1 (NT1) is caused by a loss of hypocretin/orexin transmission. Risk factors include pandemic 2009 H1N1 influenza A infection and immunization with Pandemrix®. Here, we dissect disease mechanisms and interactions with environmental triggers in a multi-ethnic sample of 6,073 cases and 84,856 controls. We fine-mapped GWAS signals within HLA (DQ0602, DQB1*03:01 and DPB1*04:02) and discovered seven novel associations (CD207, NAB1, IKZF4-ERBB3, CTSC, DENND1B, SIRPG, PRF1). Significant signals at TRA and DQB1*06:02 loci were found in 245 vaccination-related cases, who also shared polygenic risk. T cell receptor associations in NT1 modulated TRAJ*24, TRAJ*28 and TRBV*4-2 chain-usage. Partitioned heritability and immune cell enrichment analyses found genetic signals to be driven by dendritic and helper T cells. Lastly comorbidity analysis using data from FinnGen, suggests shared effects between NT1 and other autoimmune diseases. NT1 genetic variants shape autoimmunity and response to environmental triggers, including influenza A infection and immunization with Pandemrix®.

Sleep apnea syndrome comorbid with and without restless legs syndrome: differences in insomnia specific symptoms.

OBJECTIVE: Sleep Apnea Syndrome (SAS) is frequently comorbid with Restless Legs Syndrome (RLS). Both disorders are associated with disturbed sleep. However, data about insomnia specific symptoms in patients suffering from both sleep disorders (SAS-RLS) are rare. METHODS: In a restrospective design, we investigated 202 patients suffering from SAS and SAS-RLS. All patients underwent polysomnography, performed a vigilance test (Quatember-Maly), and completed the Regensburg Insomnia Scale (RIS), Epworth Sleepiness Scale (ESS), Beck Depression Inventory-II (BDI-II), and a Morning Questionnaire (FZN). Differences in insomnia specific symptoms between SAS and SAS-RLS were calculated using ANOVA. In a secondary analysis, the differences in daytime sleepiness and depression were analyzed. RESULTS: Of 202 patients, 42 (21%) had SAS-RLS. The proportion of women (60%) with SASRLS was higher than for men (40%) while men had had a higher proportion (71%) of SAS alone compared to women (29%), p < 0.0005. The RIS score was higher in SAS-RLS than in SAS. No differences were found in PSG data, ESS, BDI-II, or vigilance tests. CONCLUSIONS: Patients with both disorders SAS and RLS show a higher degree of insomnia-specific symptoms than for SAS alone and may profit from additional insomnia specific treatment.

Changes in Subjective-Objective Sleep Discrepancy Following Inpatient Cognitive Behavior Therapy for Insomnia.

Discrepancy between objective and subjective sleep parameters is a frequent symptom in persons suffering from insomnia. Since it has an impairing effect on daytime well-being and neglects possible positive objective improvements, it would be useful if it was treated. Apart from hypnotics, cognitive behavior therapy (CBT-I) is the therapy of choice for chronic forms of insomnia. However, there is limited information about whether CBT-I can also improve subjective-objective sleep discrepancy. We investigated a large sample of patients showing chronic forms of insomnia regarding their subjective-objective sleep discrepancy pre and post CBT-I. Objective sleep data were obtained from 3 nights (2 baseline nights and 1 night after therapy) using polysomnography in our sleep laboratory. All 92 patients participated in a 14-day inpatient program with CBT-I including psychoeducation about subjective-objective sleep discrepancy. Repeated measures analyses showed an improvement in subjective-objective sleep discrepancy parameters after CBT-I. Those parameters were also correlated with perceived quality of sleep. We conclude that CBT-I is a useful tool to improve subjective-objective sleep discrepancy in patients showing chronic forms of insomnia.

Retrospective multicenter matched case-control study on the risk factors for narcolepsy with special focus on vaccinations (including pandemic influenza vaccination) and infections in Germany.

OBJECTIVE: Studies associate pandemic influenza vaccination with narcolepsy. In Germany, a retrospective, multicenter, matched case-control study was performed to identify risk factors for narcolepsy, particularly regarding vaccinations (seasonal and pandemic influenza vaccination) and infections (seasonal and pandemic influenza) and to quantify the detected risks. METHODS: Patients with excessive daytime sleepiness who had been referred to a sleep center between April 2009 and December 2012 for multiple sleep latency test (MSLT) were eligible. Case report forms were validated according to the criteria for narcolepsy defined by the Brighton Collaboration (BC). Confirmed cases of narcolepsy (BC level of diagnostic certainty 1-4a) were matched with population-based controls by year of birth, gender, and place of residence. A second control group was established including patients in whom narcolepsy was definitely excluded (test-negative controls). RESULTS: A total of 103 validated cases of narcolepsy were matched with 264 population-based controls. The second control group included 29 test-negative controls. A significantly increased odd ratio (OR) to develop narcolepsy (crude OR [cOR] = 3.9, 95% confidence interval [CI] = 1.8-8.5; adjusted OR [aOR] = 4.5, 95% CI = 2.0-9.9) was detected in individuals immunized with pandemic influenza A/H1N1/v vaccine prior to symptoms onset as compared to nonvaccinated individuals. Using test-negative controls, in individuals immunized with pandemic influenza A/H1N1/v vaccine prior to symptoms onset, a nonsignificantly increased OR of narcolepsy was detected when compared to nonvaccinated individuals (whole study population, BC levels 1-4a: cOR = 1.9, 95% CI = 0.5-6.9; aOR = 1.8, 95% CI = 0.3-10.1). CONCLUSIONS: The findings of this study support an increased risk for narcolepsy after immunization with pandemic influenza A/H1N1/v vaccine.

Normal-Incidence PEEM Imaging of Propagating Modes in a Plasmonic Nanocircuit.

The design of noble-metal plasmonic devices and nanocircuitry requires a fundamental understanding and control of the interference of plasmonic modes. Here we report the first visualization of the propagation and interference of guided modes in a showcase plasmonic nanocircuit using normal-incidence nonlinear two-photon photoemission electron microscopy (PEEM). We demonstrate that in contrast to the commonly used grazing-incidence illumination scheme, normal-incidence PEEM provides a direct image of the structure's near-field intensity distribution due to the absence of beating patterns and despite the transverse character of the plasmonic modes. Based on a simple heuristic numerical model for the photoemission yield, we are able to model all experimental findings if global plane wave illumination and coupling to multiple input/output ports, and the resulting interference effects are accounted for.

The European Narcolepsy Network (EU-NN) database.

Narcolepsy with cataplexy is a rare disease with an estimated prevalence of 0.02% in European populations. Narcolepsy shares many features of rare disorders, in particular the lack of awareness of the disease with serious consequences for healthcare supply. Similar to other rare diseases, only a few European countries have registered narcolepsy cases in databases of the International Classification of Diseases or in registries of the European health authorities. A promising approach to identify disease-specific adverse health effects and needs in healthcare delivery in the field of rare diseases is to establish a distributed expert network. A first and important step is to create a database that allows collection, storage and dissemination of data on narcolepsy in a comprehensive and systematic way. Here, the first prospective web-based European narcolepsy database hosted by the European Narcolepsy Network is introduced. The database structure, standardization of data acquisition and quality control procedures are described, and an overview provided of the first 1079 patients from 18 European specialized centres. Due to its standardization this continuously increasing data pool is most promising to provide a better insight into many unsolved aspects of narcolepsy and related disorders, including clear phenotype characterization of subtypes of narcolepsy, more precise epidemiological data and knowledge on the natural history of narcolepsy, expectations about treatment effects, identification of post-marketing medication side-effects, and will contribute to improve clinical trial designs and provide facilities to further develop phase III trials.

The effect of partial sleep deprivation on computer-based measures of fitness to drive.

PURPOSE: Using a partial sleep deprivation paradigm, the aim of the study was to investigate the sensitivity of a computer-based test battery of fitness to drive to detect impairments related to sleepiness. METHODS: Forty-seven healthy subjects (34 females, mean age 26.0 ± 6.8 years) participated in a counterbalanced within-subject design of two conditions: (i) normal night sleep and (ii) partial sleep deprivation (PSD) with 4 h time in bed. For the assessment of fitness to drive, we used a validated traffic psychological test battery. Moreover, well-established measures of sleepiness highly responsive to sleep deprivation were applied: the Karolinska Sleepiness Scale (KSS), pupillography (Pupil Unrest Index (PUI) as physiological sleepiness indicator) and two sustained attention tasks (psychomotor Vigilance Task and Mackworth Clock Test). RESULTS: Subjective and physiological sleepiness were significantly increased after PSD, accompanied by large (d > 1.50 for KSS) and medium (d = 0.55 for PUI) effect sizes. Sleepiness-related performance decrements were found in both sustained attention tasks (d = 0.59-0.77). Assessing driving-related ability, PSD induced decrements only in the test domain Reaction Test (reaction time d = 0.54 and motor time d = 0.45). All other subtests-as well as the overall judgement of fitness to drive-were not significantly affected by PSD. CONCLUSION: In contrast to established tests of sustained attention and subjective sleepiness, computer-based test batteries of fitness to drive might lack sensitivity to core aspects of sleepiness as they mainly consist of short and stimulating subtests. Therefore, tasks that require sustained attention should be an essential part of traffic psychological test batteries when sleepiness is a potential issue.

Narcolepsy-Associated HLA Class I Alleles Implicate Cell-Mediated Cytotoxicity.

STUDY OBJECTIVES: Narcolepsy with cataplexy is tightly associated with the HLA class II allele DQB1*06:02. Evidence indicates a complex contribution of HLA class II genes to narcolepsy susceptibility with a recent independent association with HLA-DPB1. The cause of narcolepsy is supposed be an autoimmune attack against hypocretin-producing neurons. Despite the strong association with HLA class II, there is no evidence for CD4+ T-cell-mediated mechanism in narcolepsy. Since neurons express class I and not class II molecules, the final effector immune cells involved might include class I-restricted CD8+ T-cells. METHODS: HLA class I (A, B, and C) and II (DQB1) genotypes were analyzed in 944 European narcolepsy with cataplexy patients and in 4,043 control subjects matched by country of origin. All patients and controls were DQB1*06:02 positive and class I associations were conditioned on DQB1 alleles. RESULTS: HLA-A*11:01 (OR = 1.49 [1.18-1.87] P = 7.0*10(-4)), C*04:01 (OR = 1.34 [1.10-1.63] P = 3.23*10(-3)), and B*35:01 (OR = 1.46 [1.13-1.89] P = 3.64*10(-3)) were associated with susceptibility to narcolepsy. Analysis of polymorphic class I amino-acids revealed even stronger associations with key antigen-binding residues HLA-A-Tyr(9) (OR = 1.32 [1.15-1.52] P = 6.95*10(-5)) and HLA-C-Ser(11) (OR = 1.34 [1.15-1.57] P = 2.43*10(-4)). CONCLUSIONS: Our findings provide a genetic basis for increased susceptibility to infectious factors or an immune cytotoxic mechanism in narcolepsy, potentially targeting hypocretin neurons.

The effect of sleep deprivation on pain perception in healthy subjects: a meta-analysis.

BACKGROUND: There is strong evidence indicating an interaction between sleep and pain. However, the size of this effect, as well as the clinical relevance, is unclear. Therefore, this meta-analysis was conducted to quantify the effect of sleep deprivation on pain perception. METHODS: A systematic literature search was conducted using the electronic databases PubMed, Cochrane, Psyndex, Psycinfo, and Scopus. By conducting a random-effect model, the pooled standardized mean differences (SMDs) of sleep deprivation on pain perception was calculated. Studies that investigated any kind of sleep deprivation in conjunction with a pain measurement were included. In cases of several pain measurements within a study, the average effect size of all measures was calculated. RESULTS: Five eligible studies (N = 190) for the between-group analysis and ten studies (N = 266) for the within-group analysis were identified. Sleep deprivation showed a medium effect in the between-group analysis (SMD = 0.62; CI95: 0.12, 1.12; z = 2.43; p = 0.015) and a large effect in the within-group analysis (SMD = 1.49; CI95: 0.82, 2.17; z = 4.35; p <0.0001). The test for heterogeneity was not significant in the between-group analysis (Q = 5.29; df = 4; p = 0.2584), but it was significant in the within-group analysis (Q = 53.49; df = 9; p <0.0001). CONCLUSION: This meta-analysis confirms a medium effect (SMD = 0.62) of sleep deprivation on pain perception. As this meta-analysis is based on experimental studies in healthy subjects, the clinical relevance should be clarified.

Silica-gold bilayer-based transfer of focused ion beam-fabricated nanostructures.

The demand for using nanostructures fabricated by focused ion beam (FIB) on delicate substrates or as building blocks for complex devices motivates the development of protocols that allow FIB-fabricated nanostructures to be transferred from the original substrate to the desired target. However, transfer of FIB-fabricated nanostructures is severely hindered by FIB-induced welding of structure and substrate. Here we present two (ex and in situ) transfer methods for FIB-fabricated nanostructures based on a silica-gold bilayer evaporated onto a bulk substrate. Utilizing the poor adhesion between silica and gold, the nanostructures can be mechanically separated from the bulk substrate. For the ex situ transfer, a spin-coated poly(methyl methacrylate) film is used to carry the nanostructures so that the bilayer can be etched away after being peeled off. For the in situ transfer, using a micro-manipulator inside the FIB machine, a cut-out piece of silica on which a nanostructure has been fabricated is peeled off from the bulk substrate and thus carries the nanostructure to a target substrate. We demonstrate the performance of both methods by transferring plasmonic nano-antennas fabricated from single-crystalline gold flakes by FIB milling to a silicon wafer and to a scanning probe tip.

Are dysfunctional attitudes and beliefs about sleep unique to primary insomnia?

OBJECTIVE: Dysfunctional thinking about sleep is a central aspect in the perpetuation of primary insomnia and a target symptom of cognitive behavioral therapy for insomnia (CBT-I). Insomnia symptoms also occur in other sleep disorders, but it is not known to what extent it is related to dysfunctional thinking about sleep. METHODS: The Dysfunctional Beliefs and Attitudes about Sleep Scale (DBAS) was administered to inpatients at a sleep center. The following groups were included: 34 patients with primary insomnia (PI), 30 patients with sleep apnea syndrome (SAS), 31 patients with restless legs syndrome (RLS), 26 patients with SAS comorbid with RLS (SAS + RLS), and 24 patients with idiopathic hypersomnia or narcolepsy. Eighty-four healthy subjects served as a control group. The DBAS scores were compared across the different sleep disorders and correlated with polysomnographic (PSG) variables, subjective sleep parameters, scores of the Beck Depression Inventory (BDI), and the Regensburg Insomnia Scale (RIS; measuring psychological symptoms of insomnia). RESULTS: Compared to healthy controls, DBAS scores were increased in PI, RLS and RLS + SAS. There was a low correlation between DBAS scores and PSG variables, moderate correlations between DBAS and subjective sleep parameters and BDI scores (r = 0.528), and a high correlation between DBAS and the RIS score (r = 0.603). CONCLUSION: The observation of increased DBAS scores in other sleep disorders besides primary insomnia underscores the usefulness of a broadened diagnostic procedure and suggests that CBT-I modules may be a complementary treatment tool for these disorders.

DQB1 locus alone explains most of the risk and protection in narcolepsy with cataplexy in Europe.

STUDY OBJECTIVE: Prior research has identified five common genetic variants associated with narcolepsy with cataplexy in Caucasian patients. To replicate and/or extend these findings, we have tested HLA-DQB1, the previously identified 5 variants, and 10 other potential variants in a large European sample of narcolepsy with cataplexy subjects. DESIGN: Retrospective case-control study. SETTING: A recent study showed that over 76% of significant genome-wide association variants lie within DNase I hypersensitive sites (DHSs). From our previous GWAS, we identified 30 single nucleotide polymorphisms (SNPs) with P < 10(-4) mapping to DHSs. Ten SNPs tagging these sites, HLADQB1, and all previously reported SNPs significantly associated with narcolepsy were tested for replication. PATIENTS AND PARTICIPANTS: For GWAS, 1,261 narcolepsy patients and 1,422 HLA-DQB1*06:02-matched controls were included. For HLA study, 1,218 patients and 3,541 controls were included. MEASUREMENTS AND RESULTS: None of the top variants within DHSs were replicated. Out of the five previously reported SNPs, only rs2858884 within the HLA region (P < 2x10(-9)) and rs1154155 within the TRA locus (P < 2x10(-8)) replicated. DQB1 typing confirmed that DQB1*06:02 confers an extraordinary risk (odds ratio 251). Four protective alleles (DQB1*06:03, odds ratio 0.17, DQB1*05:01, odds ratio 0.56, DQB1*06:09 odds ratio 0.21, DQB1*02 odds ratio 0.76) were also identified. CONCLUSION: An overwhelming portion of genetic risk for narcolepsy with cataplexy is found at DQB1 locus. Since DQB1*06:02 positive subjects are at 251-fold increase in risk for narcolepsy, and all recent cases of narcolepsy after H1N1 vaccination are positive for this allele, DQB1 genotyping may be relevant to public health policy.

Shaping and spatiotemporal characterization of sub-10-fs pulses focused by a high-NA objective.

We describe a setup consisting of a 4f pulse shaper and a microscope with a high-NA objective lens and discuss the aspects most relevant for an undistorted spatiotemporal profile of the focused beam. We demonstrate shaper-assisted pulse compression in focus to a sub-10-fs duration using phase-resolved interferometric spectral modulation (PRISM). We introduce a nanostructure-based method for sub-diffraction spatiotemporal characterization of strongly focused pulses. The distortions caused by optical aberrations and space-time coupling from the shaper can be reduced by careful setup design and alignment to about 10 nm in space and 1 fs in time.

Multimode plasmon excitation and in situ analysis in top-down fabricated nanocircuits.

We experimentally demonstrate synthesis and in situ analysis of multimode plasmonic excitations in two-wire transmission lines supporting a symmetric and an antisymmetric eigenmode. To this end we irradiate an incoupling antenna with a diffraction-limited excitation spot exploiting a polarization- and position-dependent excitation efficiency. Modal analysis is performed by recording the far-field emission of two mode-specific spatially separated emission spots at the far end of the transmission line. To illustrate the power of the approach we selectively determine the group velocities of symmetric and antisymmetric contributions of a multimode ultrafast plasmon pulse.

Regensburg Insomnia Scale (RIS): a new short rating scale for the assessment of psychological symptoms and sleep in insomnia; study design: development and validation of a new short self-rating scale in a sample of 218 patients suffering from insomnia and 94 healthy controls.

BACKGROUND: The Regensburg Insomnia Scale (RIS) is a new self-rating scale to assess cognitive, emotional and behavioural aspects of psychophysiological insomnia (PI) with only ten items. A specific purpose of the new scale is the evaluation of the outcome of insomnia- specific cognitive behaviour therapy (CBT-I). METHODS: Internal consistency of the RIS has been validated in 218 patients with PI. For determining sensitivity and specificity, this sample has been compared to 94 healthy controls. Sensitivity to change and pre-post cross-validation with the Pittsburgh Sleep Quality Index (PSQI) has been tested in a separate sample of 38 patients with PI undergoing CBT-I. RESULTS: RIS distinguishes well between controls and patients with PI. Internal consistency was within a good range (Cronbach alpha = .890). RIS was sensitive for detecting improvements after CBT-I in sleep parameters and target symptoms such as sleep-related thinking. CONCLUSION: The RIS is a valid and feasible instrument for assessing psychological PI-symptoms and sleep parameters.

Narcolepsy and pregnancy: a retrospective European evaluation of 249 pregnancies.

In a retrospective cohort study undertaken in 12 European countries, 249 female narcoleptic patients with cataplexy (n = 216) and without cataplexy (n = 33) completed a self-administrated questionnaire regarding pregnancy and childbirth. The cohort was divided further into patients whose symptoms of narcolepsy started before or during pregnancy (308 pregnancies) and those in whom the first symptoms of narcolepsy appeared after delivery (106 pregnancies). Patients with narcolepsy during pregnancy were older during their first pregnancy (P < 0.001) and had a higher body mass index (BMI) prior to pregnancy (P < 0.01). Weight gain during pregnancy was higher in narcoleptic patients with cataplexy (P < 0.01). More patients with narcolepsy-cataplexy during pregnancy had impaired glucose metabolism and anaemia. Three patients experienced cataplexy during delivery. The rate of caesarean sections was higher in the narcolepsy-cataplexy group compared to the narcolepsy group (P < 0.05). The mean birth weight and gestational age of neonates were within the normal range and did not differ across groups. Neonatal care was affected adversely by symptoms of narcolepsy in 60.1% of those with narcolepsy during pregnancy. This study reports more obstetric complications in patients with narcolepsy-cataplexy during pregnancy; however, these were not severe. This group also had a higher BMI and higher incidence of impaired glucose metabolism during pregnancy. Caesarian section was conducted more frequently in narcolepsy-cataplexy patients, despite cataplexy being a rare event during delivery. Furthermore, symptoms of narcolepsy may render care of the infant more difficult.

The assessment of vigilance: normative data on the Siesta sustained attention test.

OBJECTIVE: In several modern society duties individuals have to maintain their attention or vigilance over prolonged periods of time, even if the monitoring task is monotonous. The aim of our study was to obtain reference data on the 60-minute monotonous Siesta sustained attention test. METHODS: Normative data were gathered in an age-stratified sample of 234 healthy participants (118 men; 116 women) between the ages of 20 and 79 years. The impact of age, gender, time of day, and time on task during performance was analyzed. RESULTS: At least 20 participants from each age group and gender group were tested either in the morning or in the afternoon. The sample sizes were only smaller in the age group of 70 to 79 years. There was a notable age effect on all performance measures, with an increase in reaction times and false response rates from the youngest to the oldest group as well as a decrease in correct reactions with increasing age. Statistical analysis revealed no differences in speed and accuracy measures between men and women participants. There was no notable time-of-day effect but a clear impact of time-on-task speed and of correct reactions during the course of the test. The vigilance decrement had already occurred during the first half of the test. CONCLUSIONS: Our results provide a normative database of performance parameters for different age groups in healthy adult participants. As sustained attention is sensitive to sleep loss and nonrestorative sleep, our data can be used as a reference for performance-based assessment of daytime sleepiness in participants with hypersomnia.